Electromagnetic contactor



Feb. 25, 1935. PIERCE ELECTROMAGNETIC CONTACTOR Original Filed May 20, 1930 lNVENTOR Lawrence Pierce WITNESSES: Qwew Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE ELECTROMAGNETIC CONTACTOR Lawrence Pierce, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania 6 Claims. (01. 20087) This application is a division of my copending application Serial No. 453,988, filed May 20, 1930 which became Patent No. 1,966,217 issued July 10, 1934.

My invention relates, in general, to switching devices, and, more particularly, to electro-magnetically operated contactors.

An object of my invention, generally stated, is to provide a contactor that shall be simple and emcient in operation and which may be readily and economically manufactured.

A more specific object of my invention is to provide a contactor that shall have a long life and a low maintenance expense.

Another object of my invention is to provide for effecting the opening of the contact members of an electro-magnetic contactor at high speed.

Still another object of my invention is to prevent vibration of the moving parts of a contactor and bouncing or rebounding of the contact members when opening or closing.

Other objects of my invention will be fully explained hereinafter or will be apparent to those skilled in the art.

For a fuller understanding of the nature and objects of my invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a view, in front elevation, of an electro-magnetlc contactor constructed in accordance with my invention; and Fig. 2 is a view, partly in side elevation and partly in section, of the contactor shown in Fig. 1.

Referring to the drawing, the entire contactor mechanism is mounted upon an insulating panel I0. An electro-magnet II, having a pivotallymounted armature I2, is provided for actuating a movable contact member I3 into engagement with a fixed contact member I4.

In order that the correct contact pressure may be maintained between the contact members, the movable contact member I3 is resiliently mounted on the armature I2. The fixed contact member I4 is mounted on an insulating base I5, which is carried by a bracket I6, mounted upon the panel I0.

As is the usual practice, are horns I! and I8 are mounted on the contact members I3 and I4, respectively, and a flexible shunt I9 is provided for conducting current from the movable contact member I3 to a connecting stud 20.

In order to provide a magnetic field for forcing the are, which is drawn between the contact members I3 and I4 when they are separated while carrying current away from the contact members and for causing it to travel along the surfaces of the arcing horns, an electro-magnetic blowout coil is mounted above the contact members. The blow-out coil comprises a coil member 2| which is wound around a core 22. Metallic plates 23 are mounted at the sides of the coil and serve as pole pieces to complete the magnetic circuit. As shown, one end of the coil 2| is connected to a stud 24 and the other end of the coil is connected to the fixed contact member I4.

With a view to confining the arc within substantially definite limits to prevent it from striking and burning the current carrying parts of the contactor, it is desirable to provide an arc boX 25 which substantially encloses the contact members I3 and I4, and also the arcing horns I1 and 18. The are box comprises sides 26 which are separated by cross members 21 and 28. It may be constructed of an insulating refractory material, as, for example, soapstone.

By referring to Fig. 2, it will be observed that the insulating cross member 28 is mounted above the arcing horn I8. In this embodiment of the invention, the arcing horn I8 is curved around the blowout coil 2|, in order to provide a space or pocket 29 between the cross member 28, the sides 26, and the horn I8 into which the arc is forced by the magnetic field produced by the blowout coil 2|. A space 30 is also provided between the cross member 21 and the arcing horn I'I when the contact member I3 is in the open position.

In order to provide for inspection and replacement of parts of the contactor, the arc box 25 is pivotally mounted at the top by a pin 3 I, which permits the arc box to be easily raised about the pivot point and entirely removed from the contactor if necessary.

When the magnet I I is energized, the armature I2 is biased upwardly and the contact member I3 is actuated into engagement with contact member I4. An electrical circuit is then completed from the connecting stud 24, through the blow-out coil 2I, contact members 14 and I3 and the flexible shunt I9, to the connecting stud 20. When the magnet II is deenergized, the contact member I3 drops to the position indicated by the broken lines. Upon interruption of the electrical circuit by the separation of the contact members l3 and I4, an arc is drawn between the contact members, and the current traversing said members is directed through the arc which acts as a conductor. A magnetic field is created by the blow-out coil which affects the arc in a manner similar to the force exerted upon an armature conductor in the field of an electric motor. The magnetic circuit is so designed that the magnetic field, created by the blow-out coil, will direct the arc away from the contact members and force the arc terminals to travel along the surfaces of the arc horns into the pockets 29 and 30 in a manner fully described and claimed in my above mentioned patent.

Referring particularly to Fig. 2, it will'be seen that the armature l2 is pivotally mounted on a bearing bracket 32, secured to the panel In, by means of a pin 33 and that the contact member I3 is carried by an arm 34 which is pivotally mounted on the armature 12 by means of a pin 35. A compression spring 36 is interposed be.- tween a seat 3?, provided on the armature l2, and the contact-carrying arm 34 in a manner to resiliently bias the movable contact member [3 into engagement with the fixed contact member 14 when the armature I2 is drawn towards the electro-magnet ll.

As shown, a relatively large amount of the material in the armature member I2 is concentrated at 38 near the edge of the armature farthest removed from its pivot point 33, thereby producing a hammer-like effect. When the armature IZ is in its uppermost position, and the contact members are closed against the compression spring 36, there is a space 39 between the bottom surface of the portion 38 of the armature IZ and the top surface of the contact arm 34. Therefore, when the electro-magnet H is deenergized, the armature is forced downward by the combined force of the spring 36 and gravity and the heavy or hammer-like portion 38 strikes the contact arm 34 a sharp blow at the instant of opening resulting in high speed separation of the contact members. The high speed opening of the contact members assists in rapidly extinguishing the arc, which prolongs the life of the contact members and other parts of the contactor.

With a view to reducing vibration and rebounding of the moving parts of the contactor when the contact members are opened and closed, a pair of non-magnetic rivets 40 are so disposed in the armature 12 that they will strike a stop member 4| at the center of percussion of the armature member !2 when the armature drops to its lowermost position upon the deenergization of the electro-magnet II. In this manner, vibration is reduced, which prolongs the life of the armature pin and bushings, and rebounding of the movable contact member is prevented, thereby reducing pitting of the contact members, which frequently occurred in contactors of previous types as a result of the contact members rebounding to the extent that the contact members would retouch. Rebounding of the contact members upon closing is prevented by the action of the spring 35, which forces upwardly on the contact-carrying arm 34 and downwardly on the armature member I2. 7

In order to prolong the life of the flexible shunt l9 by reducing the bending action of the shunt during the operation of the contactor, the shunt is so mounted that one end 42 is substantially in vertical alinement with the pivot point of the armature member and the other end 43 is substantially in horizontal alinement with said pivot point. Where practicable, the end 42 of the shunt may be connected at a point to the right of the pivot point of the armature member thereby suspending the shunt about the pivot point of the armature which greatly reduces the bending of the shunt. In this manner, the total movement of the shunt is uniformly distributed over its entire length, instead'of being concentrated at one point, thereby preventing breakage of the shunt which frequently occurred in previous types of contactors.

From the foregoing description, it is apparent that I have provided an electro-magnetic contactor which is efiicient in operation, may be economically manufactured, and which will have a long life and a low maintenance expense.

Since many modifications may be made in the apparatus and arrangement of parts without departing from the spirit of my invention, I do not wish to be limited other than by the scope of the appended claims.

I claim as my invention:

1. In an electro-magnetic contactor, in combination, an electro-magnet having a pivotallymounted armature member, said armature having a hammer-like portion, a fixed contact member, a movable contact member disposed to resiliently engage the fixed contact member when the armature is actuated towards the electro-magnet, and a contact-carrying arm pivotally mounted on the armature member for supporting the movable contact member, said contact-carrying arm being so mounted on the armature member that the hammer-like portion of the armature will impinge on the contact-carrying arm when the armature is actuated away from the electromagnet, thereby causing the contact members to be separated quickly.

2. In an electro-magnetic contactor, in combination, an electro-magnet having a. pivotallymounted armature member, said armature having a hammer-like portion, a fixed contact member, a movable contact member disposed to engage the fixed contact member, a contact-carrying arm pivotally mounted on the armature member for supporting the movable contact member, and a spring for resiliently biasing the movable contact member into engagement with the fixed contact member when the armature is actuated towards the electro-magnet, said contact-carrying arm being so mounted on the armature member that the hammer-like portion of the armature will impinge on the contact-carrying arm when the armature is actuated away from the electro-magnet thereby causing the contact members to be separated quickly.

3. In an electro-magnetic contactor, in combination, an electro-magnet having apivotally mounted armature member, said armature having a hammer-like portion, a fixed contact member, a movable contact member disposed to resiliently engage the fixed contact member when the armature is actuated towards the electromagnet, and a contact-carrying arm .pivotally mounted on the armature member for supporting the movable contact member, said contact-carrying arm being so mounted on the armature member that a space is provided between the armature and the contact-carrying arm when the contact members are in closed position, whereby the hammer-like portion of the armature will impinge on the contact-carrying arm when the armature is actuated away from the electro-- magnet.

4. In an electro-magnetic contactor, in combination, an electro-magnet having a pivotaily mounted armature member, said armature having a relatively large amountlof material disposed 'near the edge farthest removed from the pivot point of the armature to constitute a hammerlike portion, a fixed contact member, a movable contact member disposed to resiliently engage the fixed contact member when the armature is actuated towards the electro-magnet, and a contactcarrying arm pivotally mounted on the armature member for supporting the movable contact member, said contact-carrying arm being so mounted on the armature that the hammer-like portion of the armature will impinge on the contact-carrying arm when the armature is actuated away from the electro-magnet thereby causing the contact members to be separated quickly.

5. In an electro-magnetic contactor, in combination, an electro-magnet having a pivotally mounted armature member, a contact-carrying arm mounted on the armature, a connecting stud, and a flexible shunt having one end connected to the contact-carrying arm substantially in horizontal alinement with said stud for conducting current between the contact-carrying arm and the connecting stud, the other end of said shunt being connected to the stub substantially in vertical alinement with the pivot point of said armature member, whereby the bending movement of the shunt is distributed over its entire length.

6. In an electro-magnetic contactor, in combination, an electro-magnet having a pivotallymounted armature member, a contact-carrying arm pivotally mounted on the armature, a connecting stud, and a flexible shunt for conducting current between the contact-carrying arm and the connecting stud, one end of said shunt being connected to the stud substantially in vertical alinement with the pivot point of said armature member, and the other end of the shunt being connected to the contact-carrying arm substantially in horizontal alinement with said stud, the shunt being suspended about the pivot point of the contact-carrying arm, thereby reducing the bending action of the shunt.

LAWRENCE PIERCE. 

